1980—2017年祁连山水源涵养量时空变化特征

Spatiotemporal variation characteristics of water conservation amount in the Qilian Mountains from 1980 to 2017

祁连山是中国西北地区十分重要的生态安全屏障,也是当地极为关键的水源涵养区。基于InVEST模型中的产水量模块,对祁连山水源涵养量和时空变化进行了分析并探讨其影响因素。结果表明:祁连山多年平均产水总量和水源涵养总量约为93.03×10^(8)m^(3)和57.83×10^(8)m^(3)。从时间变化来看,水源涵养量呈上升趋势,上升速率约为0.196 mm·a^(-1);在空间上呈“东多西少”的分布格局,与年降水量的空间分布大致相同。不同土地利用类型下的水源涵养总量依次为:草地(31.87×10^(8)m^(3))>林地(16.71×10^(8)m^(3))>耕地(4.92×10^(8)m^(3))>其他用地(2.29×10^(8)m^(3))>建设用地(0.63×10^(8)m^(3))。降水量与水源涵养量在所有研究时段内均存在显著正相关性。不同时期土地利用类型的变化也会对水源涵养量产生重要影响,研究区草地面积变化对水源涵养量影响较大。根据建立的经验公式并参考已有研究成果,估算得出研究区多年冻土地下冰储量在550 km^(3)以上,在全球气候变暖的背景下,消融趋势明显。研究可为祁连山水资源合理配置和生态系统保护提供参考。

In recent years,more and more attention has been paid to the ecosystem service function,and it has gradually become a hot issue for scholars.As one of the important service functions of surface ecosystem,water conservation plays a key role in regulating regional hydrological cycle,improving surface water status and main⁃taining the normal operation of regional ecosystem.As an important ecological security barrier,the Qilian Mountains is also one of the important water conservation functional areas in Northwest China.Based on the In⁃VEST water wield model and the principle of water balance equation,the water production of each unit is calcu⁃lated by subtracting the actual evapotranspiration from the precipitation of each unit,at last,the water conserva⁃tion capacity of the study area is obtained.The model needs input of precipitation,potential evapotranspiration,soil texture,land use type,and vegetation available water grid layer.The meteorological data are from China Meteorological Data Service Center,the soil texture data are from Harmonized World Soil Database,and the soil type data are from Resource and Environment Science and Data Center,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences.The spatial and temporal variation characteris⁃tics of water yield amount and water conservation amount in the Qilian Mountains were calculated and analyzed,and the influencing factors of water conservation amount were discussed by using Pearson correlation analysis method.It is of great significance to promote the rational allocation of water resources,water management and ecosystem protection in the Qilian Mountains.The results showed that the annual average total amount of water wield and total amount of water conservation were about 93.03×10^(8)m^(3)and 57.83×10^(8)m^(3),respectively.The wa⁃ter conservation amount showed a slight upward trend and the change rate was 0.196 mm·a^(-1).The total amount of water conservation under different land use types was:grassland(31.87×10^(8)m^(3))>woodland(16.71×10^(8)m^(3))>cultivated land(4.92×10^(8)m^(3))>other land(2.29×10^(8)m^(3))>building land(0.63×10^(8)m^(3)).In the aspect of mete⁃orological elements,there is a significantly positive correlation between precipitation and water conservation amount in each period,there is a negative correlation between evapotranspiration and water conservation amount,and there is a positive correlation between average air temperature and water conservation amount,but the correlation is not significant.At the same time,the change of land use types in different periods also has an important influence on water conservation amount,and change of grassland area has a great influence on water conservation amount.While paying attention to regional climate change,land resources should be rationally de⁃veloped and utilized,and attention should be paid to the protection of its green space ecosystem.Under the back⁃ground of high and cold climate,permafrost is widely distributed in the study area,and the underground ice bur⁃ied under the geomorphology of permafrost is a special form of water body.It also plays an important role in reg⁃ulation of regional water resources and plateau ecological environment change.Therefore,the combination of surface water and underground ice storage of permafrost in this paper is helpful to grasp the overall change of wa⁃ter resources in the Qilian Mountains.In this paper,average air temperature,average surface temperature and average thickness of permafrost in the Qilian Mountains are estimated according to the empirical formula of per⁃mafrost established by predecessors.The estimated underground ice storage of permafrost in the study area is about 555.76 km^(3).As warming trend continues in the future,area of the warm permafrost will continue to in⁃crease,underground ice of the permafrost will melt at a faster rate,and its internal water storage will decrease ac⁃cordingly.The study also has important implications for assessment and management of hydrological cycles and ecosystems in the Qilian Mountains.